Jack is twice as old as Lacy. In three years, the sum of their age will be 54. How old are they now?

Aug 14, 2016

Let the age of Lucy be $x$. Then Jack's will be $2 x$.

$2 x + x = 54$

$3 x = 54$

$x = 18$

So Lucy will be $18$ in $3$ years and Jack will be $36$. So subtract $3$ to get their ages now.

Jack is $33$ now and Lucy is $15$.